Gas Dryer not heating

Dryer Repair
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1

I have an Amana Gas dryer about 3 years old. I believe it is the same as the Maytag MGD9700A. The tech info taped to the back of the dryer even references the Maytag service manual

The Dryer starts out fine and then stops heating after a couple of minutes. I initially took it apart the other night and checked a bunch of things.
-There is no blockage to the vent or airflow
-Checked the thermostats, they all measured 0 Ohms
-Checked the heating element resistance
-Checked the thermistor resistance
-Checked the resistance on the terminals of the gas valve, they were all fine

I fired it up with the front of the cabinet off and it lit up fine. I figured some connection must have just gotten loose and in my testing I had fixed it. So I put it all back together. Ran it again and it was fine at first and then stopped heating Checked the service mode for a diagnostic code and there was none.

So I let it sit over night and and tried it today. It fired up and then about 30 sec later the flame went out. Turned it off let it sit a few mintes and tried again and the flame came on and immediately went off (couple sec at most)

I tried a bunch of things and eventually I tried jumping the hi limit thermistat and it fired up and the flame stayed on for maybe 5 minutes. (significantly longer than it has stayed on since started having a problem) Then it went out which I figured was normal cycling for temperature. so I let it keep running. Then after a minute or two the ingniter starting glowing, but the gas didn’t kick in and the igniter went off. A minute later the cycle repeated, ingnitor glows but gas never kicks in.

I measured the resistance across the thermostat while it was hot and it was open (infinite).

I let it sit while I grabbed some dinner. Then tried again with Thermistat connected and same results - shuts off in <30 sec. Bypassed thermistat and again same thing, ran for about 5 minutes cooled down, ignitor started to glow, but gas never kicked in

could bypassing the termistat somehow be preventing the gas from kicking back in? I wouldn’t think so, but am can’t come up with much else

Any other ideas of what could be wrong? Could it be the gas valve if it is initally firing up? (The resistance readings across the 5 terminals are ok)

3

I would replace the gas valve coils on top of the valve. They wear out, get hot and will be intermittant.

4

I did confirm the coils on the gas valve are bad. When they cool they measure normal, but when they heat pins 1 to 2 and 2 to 3 go to open.

I also confirmed they hi limit termistat is bad. Goes to open with almost any amount of heat. It is a little concerning that both failed at the same time, but we will see what happens now that they are replaced

One question I do have is that the new coils have significantly different resistance than the original/spec sheet
1-3 reads 700 Ohms vs spec of 550
1-2 reads 1670 Ohms vs spec of 1350
3-4 reads 1600 vs spec of 1300
This seems outside normal variance to me. They seem to work fine. Any longer term issue with using these?